/dev/mem virtual device support

configname: CONFIG_DEVMEM

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>/dev/mem virtual device support
In linux kernel since version 4 (release Date: 2015-04-12)  
Say Y here if you want to support the /dev/mem device.
The /dev/mem device is used to access areas of physical
memory.
When in doubt, say "Y".